It was originally for crew and expert flyers, but it has become anybody and they don't turn anybody away. Simply that if you don't know it's there, you won't find it by yourself because it's on the arrivals level.

On TCON, I fly DCA-ORD-WEST COAST given roughly hourly service to ORD and close to that for LAX & SFO from ORD. I find that my door-to-door time from downtown DC to downtown LA / SF is almost the same flying nonstop from IAD or with a change in ORD.

I can't recall ever have waited more than 10 mins at checkpoint for UA at DCA and it's most often 1-2 people ahead of me.